1 /*
2  * Copyright (C) 2011 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 package com.android.tradefed.util;
17 
18 import java.io.PrintWriter;
19 import java.util.ArrayList;
20 import java.util.List;
21 
22 /**
23  * Helper class to display a matrix of String elements so each element column is lined up
24  */
25 public class TableFormatter {
26 
27     private int mColumnSpacing = 2;
28 
29     /**
30      * Sets the number of whitespace characters between each column.
31      *
32      * @param spacing the number of whitespace characters
33      * @return the {@link TableFormatter}
34      */
setColumnSpacing(int spacing)35     public TableFormatter setColumnSpacing(int spacing) {
36         mColumnSpacing = spacing;
37         return this;
38     }
39 
40     /**
41      * Display given String elements as an table with aligned columns.
42      *
43      * @param table a matrix of String elements. Rows can be different length
44      * @param writer the {@link PrintWriter} to dump output to
45      */
displayTable(List<List<String>> table, PrintWriter writer)46     public void displayTable(List<List<String>> table, PrintWriter writer) {
47         if (table.size() <= 0) {
48             throw new IllegalArgumentException();
49         }
50         // build index of max column sizes
51         List<Integer> maxColumnSizes = getColumnSizes(table);
52         for (List<String> rowData : table) {
53             for (int col = 0; col < rowData.size(); col++) {
54                 writer.append(rowData.get(col));
55                 int numPaddingChars = maxColumnSizes.get(col) - rowData.get(col).length();
56                 insertPadding(numPaddingChars, writer);
57             }
58             writer.println();
59         }
60     }
61 
insertPadding(int numChars, PrintWriter writer)62     private void insertPadding(int numChars, PrintWriter writer) {
63         for (int i = 0; i < numChars; i++) {
64             writer.append(' ');
65         }
66     }
67 
getColumnSizes(List<List<String>> table)68     private List<Integer> getColumnSizes(List<List<String>> table) {
69         List<Integer> maxColumnSizes = new ArrayList<Integer>();
70         for (List<String> rowData : table) {
71             for (int colIndex = 0; colIndex < rowData.size(); colIndex++) {
72                 if (colIndex >= maxColumnSizes.size()) {
73                     maxColumnSizes.add(colIndex, 0);
74                 }
75                 // add column spacing to string length so there is at least that amount of space
76                 // between columns
77                 int stringSize = rowData.get(colIndex).length() + mColumnSpacing;
78                 if (maxColumnSizes.get(colIndex) < stringSize) {
79                     maxColumnSizes.set(colIndex, stringSize);
80                 }
81             }
82         }
83 
84         return maxColumnSizes;
85     }
86 }
87